Human norovirus (HuNoV) infections are responsible for more than 95% of the non-bacterial acute gastroenteritis worldwide and more than 60% of all food-borne illnesses in the US. Evidence suggests that HuNoVs and porcine norovirus (PoNoV) possess high zoonotic potential and, since PoNoV shares the highest identity to HuNoV GII strains, suggesting that swine may serve as reservoirs HuNoV and for emergence of novel HuNoVs and porcine/human GII recombinants. Despite the major efforts, vaccines or antiviral drugs are not available. This is due in major part to the lack of a cell culture system or a small animal model for HuNoV pathogenesis. The overall goal of this proposal is to develop a Lactococcus lactis or lactic acid bacteria (LAB) as the vector to deliver NoV virus-like particles (VLPs) and protrusion (P) particles, and to develop LAB-based live NoV vaccines for clinical trials. We have shown that LAB strains expressing VLP and P particles derived from HuNoV-GII.4 induced strong protective immune responses when orally inoculated into gnotobiotic (GN) piglets, the only nonprimate animal model that accurately replicates HuNoV disease. Using this unique animal model, we will determine the dynamics of LAB colonization and the expression, uptake of the NoV VLP and P particles in gastrointestinal tract, and innate immunity induced by LAB-based vaccines. We will determine if LAB- based vaccines provide protection against challenge with homologous (HuNoV-GII) or heterologous (PoNoV-GII) viruses. Subsequently, we will determine the mechanism by which LAB-based vaccine induces NoV-specific mucosal, humoral, and cellular immune responses, and define immune correlates of homologous and heterologous protection against NoV strains. Finally, we will determine if microencapsulation and a dendritic cell (DC) targeting peptide that specifically binds mucosal antigen- presenting cells (APCs) will enhance the immunogenicity of LAB-based NoV vaccines and will protect GN piglets from virulent virus challenge. Successful completion of these studies will result in development of safe, stable and efficacious vaccine(s) for the prevention of HuNoV/PoNoV gastroenteritis in humans and swine. This project will also provide a new avenue for vaccine development for other non-cultivable food- and water-borne viruses of human and domestic animal significance.